KTO-01 Kriterien 5, 6 und 7 (01b): LoginController/State/Screen replace the
/login placeholder. Generic failure text for wrong email and password,
resend via ResendController (ResendOrigin.login), throttle and offline
banners, autofill hints, double-submit guard, validated from redirect.
Refs #1
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
